The present invention relates to a device for eliminating oil particles from the crankcase ventilation gas in an internal combustion engine, wherein the device is arranged in the flow duct of the crankcase ventilation gas that runs from the crankcase to an induction tract of the internal combustion machine and wherein the device exhibits an oil separator in the form of an outlet for the crankcase ventilation gas with a deflection of the flow, as a result of which oil particles are deposited on a baffle surface and thus eliminated from the crankcase ventilation flow.
A device for deoiling crankcase ventilation gas in an internal combustion is known from EP 1 285 152 B1, wherein the device exhibits at least one oil separator as well as a bypass duct bypassing the oil separator. In the bypass duct at least one means is provided which opens and closes the bypass duct dependent on a differential pressure. In the process the bypass duct and the means for opening and closing of the bypass duct are constructed in such a way that in the case of an opened bypass duct as a result of the deflection of the flow and impact separation a deoiling of the crankcase ventilation gas in the bypass duct is effected. In the normal operation of this device the bypass duct is however closed and the total volume flow of the crankcase ventilation gases flows through the oil separator, which is preferably constructed here as a cyclone separator. Only in the case of extraordinarily great quantities of crankcase ventilation gas is the bypass duct additionally opened, after which the oil separator, here the cyclone separator, and the bypass duct are then flowed through in parallel to the crankcase ventilation gas. With regard to the relatively fine particle sizes of the oil particles in the crankcase ventilation gas the bypass duct with the means for opening and closing the bypass duct located within possesses only a relatively poor oil separation effect, so that with this bypass duct and the means provided within for opening and closing the bypass duct only in combination with another oil separator, here preferably a cyclone separator, is a sufficient total degree of separation achieved.
A device for the separation of gas and liquid particles in a mixture of gas and fluid particles flowing in a line and a method for the separation thereof are known from DE 100 51 307 A1. This device comprises a line in which the mixture flows. A baffle element is arranged in the line which gives rise to the separating eddy current and thus separates gas on the one hand and liquid particles on the other from one another. The baffle element is preferably constructed here in the form of a baffle plate which is aligned perpendicular to the longitudinal direction of the line. Also in the case of this known device the degree of separation with regard to relatively fine particle sizes, in particular as they are present in the crankcase ventilation gas of an internal combustion engine, is relatively low. Therewith this known device is only suitable for applications in which the liquid particles are relatively large.
DE 103 20 215 A1 shows an oil separation device for an internal combustion engine, which is inserted in a flow path for blow-by gas loaded with oil particles between the crankcase and the induction tract of the internal combustion engine and which exhibits an oil separator with a narrowed outlet, through which the flow of the oil-loaded blow-by gas is conducted and deflected, wherein oil particles are separated at a wall, from which the oil particles flow back to the crankcase in an oil return. Further provision is made here that the at least one outlet is formed by a gap of small, variable gap width and great gap passage cross-sections, wherein the gap width is changed dependent on the volume flow of the blow-by gas through the gap against elastic force. The elastic force can in the process be applied by means of a coil spring or one or more spring tongues. The separation of the oil particles takes place by means of deflection and precipitation at a baffle surface, which is either a surface radially surrounding the coil spring at a distance or is a baffle surface developed at the spring tongue. Also in the case of this known device the degree of separation effect is high only in the case of relatively large oil particles due to the comparatively slight deflection of the gas flow, while it is lower for fine oil particles which predominate in the crankcase ventilation gas.
The older DE 10 2004 049 089 A1 which was published later shows a device for the separation of liquid from a gas flow of a crankcase of an internal combustion engine, with an input duct flow connected to the crankcase, an output duct flow connected to an intake manifold of the internal combustion engine and a separation valve arranged between the input duct and the output duct, which exhibits respectively a closing body that can be moved axially with regard to a valve axis and a valve seat cooperating with the closing body. In the process several separation valves are provided which are connected to each other in parallel and which serve as fine separators and/or finest separators.
Preferably the closing bodies of the separation valves are constructed disk-shaped, plate-shaped, latticed or shaped like perforated plates. In the case of an exemplary embodiment of the device in accordance with this publication the closing bodies and the valve openings are constructed latticed or shaped like perforated plates and exhibit several through openings arranged in rows and gaps, wherein valve reinforcing ribs are arranged between the through openings. The through openings of the closing bodies are displaced in such a way to the through openings of the valve openings that in the case of the resting of the closing body on the valve seat the through openings of the closing body through the valve reinforcing ribs of the valve openings and vice versa are closed. Due to the latticed structure in the case of the removal of the closing body from the valve seat many narrow valve gaps are formed, which should make possible a good fine separation.
In the case of this device it is considered disadvantageous that it exhibits a relatively low separation effect with regard to the in particular fine oil droplets carried in the gas flow. In the case of the design of the device with closing bodies and valve openings that are latticed or shaped like perforated plates there is a risk of valve float, which is unfavorable for the function of the device and which can lead to a premature wear and tear and with it failure of the device. In addition the precise geometrical correspondence between ribs on the movable element and the passages on the stationary element in practice with limited technical expenditure can only be achieved with difficulty. A precise radial suspension and anti-twist protection of the unit are required for this. Such an arrangement is impaired in its function through deposits and dirt accumulations.
A pneumatic pressure control valve is known from the older DE 20 2004 013 123 U1 which was published later, said pressure control valve being arranged in the flow of a gas line, whose outlet can be changed automatically by means of the pressure control valve in dependency on the differential pressure between one or more gas pressures present at least one inlet of the pressure control valve. In the process a regulating membrane is provided in the pressure control valve which is impacted on the one hand by a reference pressure and on the other hand by the gas pressure or the gas pressures as well as by a control spring, as a result of which in the case of the change of the reference pressure between the regions adjacent to the regulating membrane the regulating membrane is adjusted and the regulating membrane itself or a closing body actuated by the regulating membrane enlarges or reduces the outlet through a flow cross-section of the pressure control valve. In the process a structure of the pressure control valve adjacent to the flow cross-section on the membrane side forms a stop for the regulating membrane or for the closing body in its closed position. Further at least one preliminary stop is arranged in the pressure control valve in such a way that in the case of the movement of the regulating membrane in closing direction the regulating membrane or the closing body comes into contact with the preliminary stop first and wherein in the case of further movement of the regulating membrane in closing direction the regulating membrane or the closing body then under (further) elastic flexible deformation further reduces the outlet and reaches a final position also in contact with the stop. Further in the process the preliminary stop is formed by at least one open preliminary stop structure lying in the flow cross-section plane on the membrane or closing body side.
With the plane, open preliminary stop structure the pressure control valve, along with its pressure control function, should additionally be given the function of a liquid separator at least to a certain extent. The open preliminary stop structure lies in the flow cross-section, so that a gas with liquid droplets flows first in radial direction from the outside to the inside parallel to the membrane or closing body and then is deflected in axial direction and flows through the individual openings of the preliminary stop structure. In the process at least the larger liquid droplets impact within the openings of the preliminary stop on the latter and can thus be separated from the gas flow.
In the case of this pressure control valve the preliminary stop structure serves first and foremost the purpose of influencing the pressure control behavior in terms of a most constant possible pressure on the inlet side of the pressure control valve. The membrane or the closing body do not form a baffle surface here, because the gas flow direction runs first parallel to the plane of the membrane or of the closing body radially from the outside to the inside and then is deflected in an axial direction through the openings of the preliminary stop structure. Additionally, to achieve the previously mentioned separation effect for liquid droplets carried in the gas an enlarged installation space is necessary, which in the case of narrow space conditions can lead to accommodation problems.
For the present invention therefore one is confronted with the problem of creating a device of the initially named type which avoids the foregoing described disadvantages and with which in the case of a slight technical expenditure an improved degree of separation effect, also with regard to fine oil particles, is achieved. In the process the device should also serve as the controller for controlling the gas volume flows conducted away from the crankcase.